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Abstract:

Provided is a polyurethane resin powder composition for slush molding
from which an outer skin for an instrument panel can be produced, the
outer skin not interfering with deployment of an airbag. More
specifically, provided is a polyurethane resin powder composition (D) for
slush molding comprising perfectly spherical thermoplastic polyurethane
resin particles (A) obtained by reacting a polyester diol component (J)
and a diisocyanate component (F), a plasticizer (B), and a vinyl-type
copolymer fine particles (C) having a crosslinked structure, wherein the
polyester diol component (J) comprises a polyester diol (J1) comprising
an aromatic dicarboxylic acid (E) and ethylene glycol as essential
constituent units, a ratio of volume average particle sizes of (A) and
(C), (A):(C), is 200:1 to 2000:1, and an extent of surface coverage of a
surface of (A) with (C) {Equation (1)} is 20 to 80%.
[Expression 1]
Extent of surface coverage (%)=[number of particles of
(C)]×[average cross section area of one particle of (C)]/surface
area of (A)×100 (1)

Claims:

1. A polyurethane resin powder composition (D) for slush molding
comprising perfectly spherical thermoplastic polyurethane resin particles
(A) obtained by reacting a polyester diol component (J) and a
diisocyanate component (F), a plasticizer (B), and a vinyl-type copolymer
fine particles (C) having a crosslinked structure, wherein the polyester
diol component (J) comprises a polyester diol (J1) comprising an aromatic
dicarboxylic acid (E) and ethylene glycol as essential constituent units,
a ratio of volume average particle sizes of (A) and (C), (A):(C), is
200:1 to 2000:1, and an extent of surface coverage of a surface of (A)
with (C) {Equation (1)} is 20 to 80%. [ Expression 1 ]
Extent of surface coverage ( %
) = [ number of particles of ( C )
] × [ average cross section area
of one part icl es of ( C ) ]
surface area of ( A ) × 100 ( 1 )
##EQU00003## [In the above-described Equation (1), the number of
particles of (C) is calculated by dividing an additive amount (weight) of
(C) by a product of average volume of one particle of (C), obtained as
described below, and true specific gravity of (C). The average volume of
one particle of (C) and the average cross section area of one particle of
(C) are calculated from a radius of (C), the radius being determined by
observing (C), which has been crushed to primary particles, with a
scanning electron microscope. The surface areas of (A) is obtained by
dividing a particle size distribution obtained by a particle size
analyzer into 30 to 60 sections, calculating the surface area of (A) for
respective divided sections from a particle size and a frequency obtained
from a center value of distribution for each divided section, and
calculating the surface area of (A) from a sum of these surface areas.]

2. The resin powder composition (D) according to claim 1, wherein the
vinyl-type copolymer fine particles (C) are a copolymer of an
alkyl(meth)acrylate and a polyfunctional (meth)acrylate of a polyhydric
alcohol.

4. The resin powder composition (D) according to claim 1, wherein a
volume average particle size of the vinyl-type copolymer fine particles
(C) is 50 to 500 nm.

5. A process for producing the polyurethane resin powder composition (D)
for slush molding according to claim 1, comprising the steps of:
impregnating the thermoplastic polyurethane resin particles (A) with a
plasticizer (B); thereafter adding the vinyl-type copolymer fine
particles (C); and mixing the particles by stirring at a peripheral speed
of an impeller of 1.0 to 2.2 m/sec until 20 to 80% of the surface of (A)
becomes covered with (C).

Description:

[0002] In recent years, a thermoplastic polyurethane resin is being used
for an instrument panel which is an automotive interior component,
because the resin makes it possible to mold a product with a complex
shape easily, to obtain uniform wall thickness, and to realize a good
yield rate of material. In order to deploy an airbag stored under the
instrument panel, a rupture opening is provided on the instrument panel.
Fabrication of the rupture opening is carried out, from the standpoint of
design characteristics, by a method of cutting a slit on the rear side of
the instrument panel by means of a hot knife (Patent Literature Nos. 1
and 2).

[0005] When the polyurethane resin powder composition for slush molding is
molded into an instrument panel, it is known that, if a degree of tensile
elongation of an outer skin of the instrument panel is 600% or more,
there is a fear that, at the time of airbag deployment, the pressure to
open the airbag is consumed in elongation of the outer skin and,
depending on the situation, the airbag does not deploy. Further, although
as a method to suppress the elongation, there can be mentioned a method
where the elongation is controlled by making a fracture point by adding
inorganic fine particles, which do not dissolve at the temperature of
slush molding, to the outer skin, this method is known to result in lower
resin strength and occurrence of a trouble that, at the time of airbag
deployment, the instrument panel ruptures at a position other than the
rupture opening.

[0006] The problem which the present invention tries to solve is to
provide a polyurethane resin powder composition for slush molding, which
makes it possible to produce an outer skin for an instrument panel, the
outer skin having a degree of tensile elongation of less than 600%, being
free from a trouble that the resin is weak and, at the time of airbag
deployment, the instrument panel ruptures at a position other than the
rupture opening, and thus not interfering with deployment of an airbag.

Means for Solving the Problems

[0007] The present inventors conducted diligent research and, as a result,
reached completion of the present invention. The present invention is a
polyurethane resin powder composition (D) for slush molding comprising
perfectly spherical thermoplastic polyurethane resin particles (A)
obtained by reacting a polyester diol component (J) and a diisocyanate
component (F), a plasticizer (B), and vinyl-type copolymer fine particles
(C) having a crosslinked structure, wherein the polyester diol component
(J) comprises a polyester diol (J1) comprising an aromatic dicarboxylic
acid (E) and ethylene glycol as essential constituent units, a ratio of
volume average particle sizes of (A) and (C), (A):(C), is 200:1 to
2,000:1, and an extent of surface coverage of the surface of (A) with (C)
{Equation (1)} is 20 to 80%; a polyurethane resin molded article obtained
by molding the composition (D); and a process for producing the
composition (D).

[0008] [In the above-described Equation (1), the number of particles of
(C) is calculated by dividing an additive amount (weight) of (C) by a
product of an average volume of one particle of (C), obtained as
described below, and true specific gravity of (C). The average volume of
one particle of (C) and the average cross section area of one particle of
(C) are calculated from a radius of a primary particle of (C), the radius
being determined by observing (C), which has been crushed to primary
particles, with a scanning electron microscope. The surface area of (A)
is obtained by dividing a particle size distribution obtained by a
particle size analyzer into 30 to 60 sections, calculating the surface
areas of (A) for respective divided sections from a particle size and a
frequency obtained from a center value of distribution for each divided
section, and calculating the surface area of (A) from a sum of these
surface areas.

Effects of the Invention

[0009] The outer skin for the instrument panel, obtained by slush molding
the polyurethane resin powder composition (D) for slush molding of the
present invention, has a degree of tensile elongation of less than 600%.
It is also free from a trouble that the resin strength is low and, at the
time of airbag deployment, the instrument panel ruptures at a position
other than the rupture opening and has excellent airbag deployment
performance.

[0013] The polyester diol (J1) is obtained by reacting ethylene glycol and
an aromatic dicarboxylic acid (E) as essential components. The polyester
diol (JI) can be obtained by a dehydration condensation reaction of
ethylene glycol and an aromatic dicarboxylic acid (E) or by a reaction of
ethylene glycol and an ester-forming derivative of (E) [acid anhydrides
(phthalic anhydride and the like), lower alkyl esters (dimethyl
terephthalate, dimethyl isophthalate, dimethyl orthophthalate, and the
like), and acid halides (phthalic acid chloride and the like)].

[0014] The aromatic dicarboxylic acid (E) includes isophthalic acid,
terephthalic acid, orthophthalic acid, and the like. The dicarboxylic
acid (E) may be a single component or a combination of two or more
components.

[0015] Among the polyester diols (J1), preferable ones from the standpoint
of handling include, for example, a polyester diol composed of ethylene
glycol and terephthalic acid/isophthalic acid (=50/50 by molar ratio), a
polyester diol composed of ethylene glycol and terephthalic
acid/orthophthalic acid (=50/50 by molar ratio), and the like. The
number-average molecular weight of these is preferably 800 to 10,000,
more preferably 1,000 to 4,000, and most preferably 1,500 to 3,000.

[0016] In addition to (J1), the polyester diol component (J) may comprise
the following polyester diol (K). The content of (K) based on the total
weight of (J) is, from the standpoint of a balance between tensile
strength and elongation, preferably 0 to 95 weight %, more preferably 50
to 90 weight %, and most preferably 60 to 80 weight %.

[0020] The polyester diol (K2) includes a polyester diol obtained by
polymerizing a lactone monomer (lactones having 4 to 12 carbon atoms such
as, for example, γ-butyrolactone, γ-valerolactone,
ε-caplolactone, and a mixture of two or more of these).

[0026] (v) modified products of these diisocyanates (modified products of
diisocyanates having carbodiimide groups, uretdione groups, uretimine
groups, urea groups, and the like); and mixtures of two or more of these.

[0027] Preferable among these are the aliphatic diisocyanates or the
alicyclic diisocyanates, and especially preferable are HDI, IPDI, and
hydrogenated MDI.

[0028] The thermoplastic polyurethane resin particles (A) can be produced,
for example, by the following process.

[0029] In the presence of water and a dispersion stabilizer, a ketimine
compound of a diamine, which is a chain-extender, is hydrolyzed in water
to yield a diamine, and the diamine and a urethane prepolymer having
terminal isocyanate groups are reacted to obtain a polyurethane resin.

[0030] The reaction temperature at which an isocyanate-terminated urethane
prepolymer is produced may be the same as the temperature usually
employed when carrying out urethanization. When a solvent is employed,
the reaction temperature is usually 20° C. to 100° C. and,
when a solvent is not used, the reaction temperature is usually
20° C. to 220° C., and preferably 80° C. to
200° C. By reacting the polyester diol component (J) and the
diisocyanate component (F) so that the molar ratio of the hydroxyl group
and the isocyanate group becomes 1:1.2 to 1:1.6, the
isocyanate-terminated urethane prepolymer can be obtained.

[0031] The chain extension reaction is preferably carried out at 20 to
120° C. for 1 to 20 hours, and the equivalent ratio of the
terminal isocyanate of the urethane prepolymer and the diamine is
preferably 1:0.8 to 1:1.2.

[0032] As the dispersion stabilizer, preferable are anionic, nonionic, and
cationic dispersants, and more preferable are the anionic ones. Examples
of the dispersion stabilizer include, for example, a metal salt of a
copolymer of an unsaturated carboxylic acid and an olefin, and the like.

[0033] Subsequently, a dispersion obtained is filtered and dried to obtain
the thermoplastic polyurethane resin particles (A). Specifically, for
example, there can be used those obtained by a process described in JP-A
No. H8-120041 and the like.

[0034] The resin particles (A) can also be produced by a process where the
above-described isocyanate-terminated urethane prepolymer is subjected to
a chain extension reaction in the presence of a nonpolar organic solvent
and a dispersion stabilizer.

[0035] In the perfectly spherical thermoplastic polyurethane resin
particles (A), the term "perfectly spherical" is defined to mean
particles having a shape factor, SF2, of 100 to 115.

[0036] Such polyurethane particles can be obtained, for example, by using
a process for production of a perfectly spherical resin particle
dispersion (the process described in Japanese Patent No. 4289720),
comprising: feeding a liquid dispersion phase comprising an
isocyanate-terminated polyurethane prepolymer and a dispersion medium
comprising only water or a combination of water and one or more selected
from the group consisting of alcohols, dimethyl formamide,
tetrahydrofuran, cellosolves, and lower ketones; dispersing the above by
high-speed rotation of an agitating blade; and, at the same time,
reacting the urethane prepolymer with a curing agent (a ketimine
compound).

[0037] The shape factor, SF2, indicates a proportion of irregularity in
the shape of a particle. It is a value represented by the following
Equation (2), obtained by dividing a square of a perimeter, PERI, of a
figure formed when the particle is projected on a two-dimensional plane
by the area of the figure, AREA, and multiplying the result by 100/4π:

SF2={(PERI)2/(AREA)}×(100/4π) (2)

[0038] As the value of SF2 becomes larger, the irregularity of the surface
of the urethane particle becomes more pronounced.

[0039] Measurement of the shape factor includes a method where a picture
of a particle is taken by a scanning electron microscope (S-800:
manufactured by Hitachi, Ltd.) and the picture is analyzed by
introduction into an image analyzer (LUSEX 3: manufactured by NIRECO
Corporation); a method where the measurement is made by using a flow
particle image analyzer (FPIA-3000: manufactured by Sysmex Corporation);
and the like.

[0041] The content of the plasticizer (B) relative to the thermoplastic
polyurethane resin particles (A) is, from the standpoint of elongation,
preferably 1 to 30 weight %, more preferably 3 to 20 weight %, and most
preferably 5 to 10 weight %.

[0042] The vinyl-type copolymer fine particles (C) having a crosslinked
structure, which are used in the present invention, have a crosslinked
structure to an extent that they become insoluble at a temperature of the
slush molding.

[0043] The fine particles (C) include, for example, a copolymer of an
alkyl(meth)acrylate and a polyfunctional (meth)acrylate of a polyhydric
alcohol.

[0044] The alkyl(meth)acrylate includes an alkyl(meth)acrylate having an
alkyl group having 1 to 50 carbon atoms, for example,
methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,
butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, dodecyl(meth)acrylate,
hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, eicosyl(meth)acrylate,
and the like.

[0046] Among these, from the standpoint of compatibility with urethane
resins, preferable is a copolymer of methyl methacrylate and ethylene
glycol dimethacrylate.

[0047] From the standpoint of controlling the extent of surface coverage
to 20 to 80%, the content of the vinyl-type copolymer fine particles (C)
having a crosslinked structure, relative to 100 weight parts of the
thermoplastic polyurethane resin particles (A), is, for example, 0.1 to
0.8 weight part when the primary particle size of the vinyl-type
copolymer fine particle (C) is 50 to 200 nm; 0.2 to 1.3 weight parts when
the primary particle size of (C) is 200 to 300 nm; 0.2 to 1.7 weight
parts when the primary particle size of (C) is 300 to 400 nm; and 0.3 to
2.1 weight parts when the primary particle size of (C) is 400 to 500 nm.

[0048] The volume average particle size of the above-described (C) is,
from the standpoints of an effect of decreasing the degree of elongation
of the molded article and fluidity (powder flowability) of the resin
powder composition, preferably 50 to 500 nm, more preferably 80 to 400
nm, and most preferably 100 to 300 nm.

[0049] The shape of the above-described (C) is not particularly limited,
but from the aspect of material flowability at the time of molding, it is
desirably spherical or close to it.

[0050] A ratio of the volume average particle sizes of the thermoplastic
polyurethane resin particles (A) and the vinyl-type copolymer fine
particles (C) having a cross-linked structure of the present invention,
(A):(C), is preferably 200:1 to 2000:1, and more preferably 400:1 to 1900
to 1. This range is preferable in that, within the range, it becomes easy
to control the extent of surface coverage in the mixed particles of (A)
and (C) between 20 to 80%.

[0051] Here, the volume average particle size refers to a value of the
particle size corresponding to 50% passing as measured by a laser
diffraction/scattering particle size/particle size distribution measuring
apparatus (hereinafter described as the particle size analyzer).

[0052] With regard to the measurement method, a 20 g sample of particles
is added to 100 ml of a 2% aqueous solution of SANSPEARL PS-8 (produced
by Sanyo Chemical Ind., Ltd.) and the mixture is stirred for 5 minutes or
more. A sample of 0.3 to 0.5 ml is taken out and loaded on the particle
size analyzer, and the particle size distribution is measured. The
measuring apparatus includes, for example, Microtrack HRA Particle Size
Analyzer 9320-X100 (manufactured by Nikkiso Co., Ltd.) and the like.

[0053] In the polyurethane resin powder composition (D) for slush molding
of the present invention, the surface of the perfectly spherical
thermoplastic polyurethane resin particles (A) contained therein is
covered with the vinyl copolymer fine particles (C) having a crosslinked
structure, wherein the extent of surface coverage is 20 to 80%.

[0054] The above-described extent of surface coverage of the surface of
the (A) with (C) is obtained from the following Equation (1).

[0055] In the above-described Equation (1), the number of particles of (C)
is calculated by dividing the amount (weight) of (C) added by a product
of an average volume of one particle of (C), obtained as described below,
and true specific gravity of (C). The average volume of one particle of
(C) and the average cross section area of one particle of (C) are
calculated from a radius of a primary particle of (C), the radius being
determined by observing (C), which has been crushed to primary particles,
with a scanning electron microscope. The radius of the primary particle
of (C) is calculated by magnifying the particles by means of a scanning
electron microscope to such an extent that the size of one particle can
be observed, selecting about 50 particles randomly and measuring radii
thereof, and computing the average of these values.

[0056] To crush (C), it is only necessary, for example, to add a small
amount of (C) to (A) and to mix them for about 5 minutes by a coffee mill
and the like.

[0057] The surface area of (A) is obtained by dividing a particle size
distribution obtained by a particle size analyzer into 30 to 60 sections,
calculating the surface areas of (A) for respective divided sections from
the particle size and a frequency obtained from a center value of
distribution for each divided section, and calculating the surface area
of (A) from a sum of these surface areas.

[0058] When the extent of surface coverage of the surface of (A) with (C)
is less than 20%, the effect of decreasing elongation is small and the
degree of elongation of the outer skin becomes 600% or more, resulting in
occurrence of a trouble at the time of airbag deployment. When the extent
of coverage exceeds 80%, the vinyl copolymer fine particles which do not
dissolve at the molding temperature become the fracture points, resulting
in weaker strength of the polyurethane resin and occurrence of a trouble
that, at the time of airbag deployment, the airbag deploys from a
position other than the rupture opening. The extent of surface coverage
is 20 to 80%, and preferably 30 to 50%.

[0059] The polyurethane resin powder composition (D) for slush molding of
the present invention is obtained by a process comprising impregnating
the thermoplastic polyurethane resin particles (A) with the plasticizer
(B), thereafter cooling the particles, and adding thereto at room
temperature the vinyl-type copolymer fine particles (C) having a
crosslinked structure.

[0060] The primary particle size of (C) contributes significantly to the
additive amount of (C) to cover (A). For example, (D) can be produced by
adding 0.1 to 0.8 weight part of (C) relative to 100 weight parts of (A),
when the primary particle size of the vinyl-type copolymer fine particles
(C) is 50 to 200 nm; adding 0.2 to 1.3 weight parts of (C) relative to
100 weight parts of (A), when the primary particle size of the vinyl-type
copolymer fine particles (C) is 200 to 300 nm; adding 0.2 to 1.7 weight
parts of (C) relative to 100 weight parts of (A), when the primary
particle size of the vinyl copolymer fine particles (C) is 300 to 400 nm;
and adding 0.3 to 2.1 weight parts of (C) relative to 100 weight parts of
(A), when the primary particle size of the vinyl-type copolymer fine
particles (C) is 400 to 500 nm.

[0061] In order to cover the surface of the urethane resin particles with
above-described (C) to the extent of 20 to 80%, it is preferable to stir
the particles at a peripheral speed of an impeller of 1.0 to 2.2 m/sec by
the under-mentioned mixing apparatus.

[0062] The polyurethane resin powder composition (D) for slush molding of
the present invention may comprise an additive (G) in addition to the
thermoplastic polyurethane resin particles (A), the plasticizer (B), and
the vinyl-type copolymer fine particles (C). The content of (G), relative
to 100 weight parts of (A), is 0 to 50 weight parts.

[0063] As (G), there may be mentioned an inorganic filler, a pigment, a
demolding agent, a stabilizer, an antiblocking agent, a dispersant, and
the like.

[0065] The volume average particle size (μm) of the inorganic filler
is, from the standpoint of dispersibility in the thermoplastic
polyurethane resin particles (A), preferably 0.1 to 30, more preferably 1
to 20, and especially preferably 5 to 10.

[0066] The additive amount of the inorganic filler, relative to 100 weight
parts of (A), is preferably 0 to 40 weight parts, and more preferably 1
to 20 weight parts.

[0067] The pigment particles are not particularly limited and there can be
used heretofore known organic pigments and/or inorganic pigments. These
are blended, relative to 100 weight parts of (A), usually in an amount of
10 weight parts or less, and preferably in an amount of 0.01 to 5 weight
parts. The organic pigments include, for example, insoluble or soluble
azo pigments, copper phthalocyanine-type pigments, quinacridone-type
pigments, and the like. The inorganic pigments include, for example,
chromates, ferrocyanide compounds, metal oxides (titanium oxide, iron
oxide, zinc oxide, aluminum oxide, and the like), metal salts [sulfates
(barium sulfate and the like), silicates (calcium silicate, magnesium
silicate, and the like), carbonates (calcium carbonate, magnesium
carbonate, and the like), phosphates (calcium phosphate, magnesium
phosphate, and the like), and the like], metal powder (aluminum powder,
iron powder, nickel powder, copper powder, and the like), carbon black,
and the like. The volume average particle size of the pigments is not
particularly limited but it is usually 0.2 to 5.0 μm, and preferably
0.5 to 1 μm.

[0068] The additive amount of the pigment particles, relative to 100 parts
by weight of (A), is preferably 0 to 5 weight parts, and more preferably
1 to 3 weight parts.

[0070] The additive amount of the demolding agent, relative to 100 weight
parts of (A), is preferably 0 to 1 weight part, and more preferably 0.1
to 0.5 weight part.

[0071] As the stabilizer, there can be used a compound having in the
molecule a carbon-carbon double bond (an ethylene bond and the like,
which may have a substituent) (excluding, however, double bonds in the
aromatic ring), a carbon-carbon triple bond (an acetylene bond, which may
have a substituent), or the like. Included are esters of (meth)acrylic
acid and polyhydric alcohols (2- to 10-valent polyhydric alcohols;
hereinafter, the same shall apply) [ethylene glycol di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, pentaerythritol
tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, and the like];
esters of (meth)allyl alcohol and 2- to 6-valent polybasic carboxylic
acids (diallyl phthalate, triallyl trimellitate, and the like);
poly(meth)allyl ethers of polyhydric alcohols [pentaerythritol(meth)allyl
ether and the like]; polyvinyl ethers of polyhydric alcohols (ethylene
glycol divinyl ether and the like); polypropenyl ethers of polyhydric
alcohols (ethylene glycol dipropenyl ether and the like);
polyvinylbenzene (divinylbenzene and the like); mixtures of two or more
of these; and the like.

[0072] Among these, from the standpoint of stability (radical
polymerization rate), preferable are esters of (meth)acrylic acid and
polyhydric alcohols, and more preferable are trimethylolpropane
tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and
dipentaerythritol penta(meth)acrylate.

[0073] The additive amount of the stabilizer, relative to 100 weight parts
of (A), is preferably 0 to 20 weight parts, and more preferably 1 to 15
weight parts.

[0074] In the polyurethane resin powder composition (D) for slush molding
of the present invention, there can be used, as a powder fluidity
improver and an antiblocking agent, heretofore known inorganic
antiblocking agents, organic antiblocking agents, and the like. The
inorganic antiblocking agents include silica, talc, titanium oxide,
calcium carbonate, and the like. The organic antiblocking agents include
thermosetting resins having a particle size of 10 μm or less
(thermosetting polyurethane resins, guanamine-type resins, epoxy-type
resins, and the like) and thermoplastic resins having a particle size of
10 μm or less [thermoplastic polyurethane urea resins,
poly(meth)acrylate resins, and the like], and the like.

[0075] The additive amount of the antiblocking agent (fluidity improver),
relative to 100 weight parts of (A), is preferably 0 to 5 weight parts,
and more preferably 0.2 to 1 weight part.

[0076] As the mixing apparatus used when manufacturing the polyurethane
resin powder composition (D) for slush molding, there can be used
heretofore known powder mixing apparatuses, including any of rotating
container-type mixers, fixed container-type mixers, and hydrokinetic
mixers. For example, there is well known a process to dry blend powders
by using, as a fixed container-type mixer, a high-speed flow mixer, a
multi-shaft paddle-type mixer, a high-speed shearing mixing apparatus
[Henschel Mixer (registered trade mark) and the like], a low-speed mixing
apparatus (planetary mixer and the like), or a cone-shaped screw mixer
[Nauta Mixer (registered trademark) and the like]. Among these processes,
it is preferable to use the multi-shaft paddle-type mixer, the low-speed
mixing apparatus (planetary mixer and the like), and the cone-shaped
screw mixer [Nauta Mixer (registered trademark; hereinafter this
annotation will be omitted) and the like].

[0077] The volume average particle size of the thermoplastic polyurethane
resin particles (A) of the present invention is usually 0.1 to 500 μm.
However, in order for the effect of the present invention to be fully
produced, it is preferably 10 to 300 μm, and more preferably 100 to
200 μm.

[0078] As an example of the polyurethane resin molded article obtained by
molding the polyurethane resin powder composition (D) for slush molding
of the present invention, there may, for example, be mentioned an outer
skin obtained by slush molding the polyurethane resin powder composition
(D) for slush molding. Slush molding can suitably be carried out, for
example, by a method, comprising vibrating and rotating a box containing
(D) and a heated mold together, melting and flowing (D) in the mold, and
thereafter cooling and solidifying (D) to manufacture the outer skin.

[0079] Heretofore, the mold temperature when slush molding is carried out
using a polyurethane resin powder composition for slush molding has been
generally preferably 200 to 300° C., and more preferably 230 to
280° C. However, the polyurethane resin powder composition (D) for
slush molding of the present invention can be molded at a lower
temperature and the mold temperature is preferably 180 to 270° C.,
and more preferably 200 to 250° C.

[0080] The thickness of the outer skin is preferably 0.4 to 1.2 mm. The
outer skin can be fabricated into a polyurethane resin molded article
having the outer skin by setting the outer skin in the foaming mold so
that its surface comes in contact with the mold and casting polyurethane
foam to form a foam layer of 5 mm to 15 mm thickness on the rear side of
the outer skin.

[0081] The polyurethane resin molded article of the present invention is
suitably used for automotive interior materials, for example, instrument
panels, door trims, and the like.

EXAMPLES

[0082] Hereinafter, the present invention will be further described by way
of examples; however, the present invention is not limited to these. In
the following description, "part(s)" represents part(s) by weight.

Production Example 1

Production of an MEK Ketimine Compound of a Diamine

[0083] While refluxing hexamethylenediamine and excessive amount of MEK
(methyl ethyl ketone, 4 times in mole relative to the amount of the
diamine) at 80° C. for 24 hours, water generated was removed to
the outside of the system. Then, under a reduced pressure, unreacted MEK
was removed to obtain an MEK ketimine compound.

Production Example 2

[0084] Production of Polyethylene Phthalate Diol (terephthalic
acid/orthophthalic acid=50/50) (J1-1) of which number average molecular
weight (hereinafter referred to as "Mn") is 2500

[0085] Into a reaction vessel equipped with a condenser tube, a stirrer
and a nitrogen-inlet tube were charged 393 parts of terephthalic acid,
393 parts of isophthalic acid and 606 parts of ethylene glycol, and under
a nitrogen flow, a reaction was carried out for 5 hours at 210° C.
removing generated water. Then, the reaction was performed under reduced
pressure of 5 to 20 mmHg and polyethylene phthalate diol (J1-1) was taken
out when it reached the specified softening point. The amount of
recovered ethylene glycol was 270 parts. A hydroxyl value of the obtained
polyethylene phthalate diol was measured and the Mn was calculated to be
2500.

Production Example 3

Production of Prepolymer Solution (U-1)

[0086] Into a reaction vessel equipped with a thermometer, a stirrer and a
nitrogen-blowing tube were charged polyethylene phthalate diol (J1-1)
(304 parts), polybutylene adipate (1216 parts) having an Mn of 1000 and
1-octanol (10 parts), and then the inside of the vessel was purged with
nitrogen. Thereafter, while stirred, the mixture was heated to
110° C. to be melted, and then the mixture was cooled to
60° C. Subsequently, thereinto was charged hexamethylene
diisocyanate (312 parts), and the reaction was performed at 85° C.
for 10 hours. Next, after the system was cooled to 60° C., thereto
were added tetrahydrofuran (336 parts), a stabilizer (4.5 parts) [IRGANOX
1010, manufactured by Ciba Specialty Chemicals Ltd.], and carbon black
(50 parts). The components were mixed with each other evenly to obtain a
prepolymer solution (U-1). The NCO content of the resultant prepolymer
solution was 1.6 weight %.

Production Example 4

Production of Thermoplastic Polyurethane Resin Particles (A-1)

[0087] Into a reaction vessel were charged and mixed the prepolymer
solution (U-1) obtained in the production example 3 (100 parts) and the
MEK ketimine compound obtained in the production example 1 (0.7 parts),
and thereto was added 300 parts of an aqueous solution in which a
polycarboxylic acid type anionic surfactant (Sansparl PS-8, manufactured
by Sanyo Chemical Ind., Ltd. (30 parts)) was dissolved. An Ultra
Disperser manufactured by YAMATO Scientific Co., Ltd. was then used to
mix these components at a rotation number of 6000 rpm for 1 minute. The
mixture was then transferred to a reaction vessel equipped with a
thermometer, a stirrer and a nitrogen blowing tube. After the inside of
the vessel was purged with nitrogen, the reaction was performed under
stirring at 50° C. for 10 hours. After the reaction was completed,
the resultant was separated by filtration and dried to obtain
thermoplastic polyurethane resin particles (A-1). The (A-1) had an Mn of
20000, a concentration of urea group of 2.6 weight % and a volume average
particle size of 140 μm.

Production Example 5

Production of Thermoplastic Polyurethane Resin Particles (A-2)

[0088] Into a reaction vessel were charged and mixed the prepolymer
solution (U-1) obtained in the production example 3 (100 parts) and the
MEK ketimine compound obtained in the production example 1 (0.7 parts),
and thereto was added 300 parts of an aqueous solution in which a
polycarboxylic acid type anionic surfactant (Sansparl PS-8, manufactured
by Sanyo Chemical Ind., Ltd. (30 parts)) was dissolved. An Ultra
Disperser manufactured by YAMATO Scientific Co., Ltd. was then used to
mix these components at a rotation number of 4000 rpm for 1 minute. The
mixture was then transferred to a reaction vessel equipped with a
thermometer, a stirrer and a nitrogen blowing tube. After the inside of
the vessel was purged with nitrogen, the reaction was performed under
stirring at 50° C. for 10 hours. After the reaction was completed,
the resultant was separated by filtration and dried to obtain
thermoplastic polyurethane resin particles (A-2). The (A-2) had an Mn of
20000, a concentration of urea group of 2.6 weight % and a volume average
particle size of 190 μm.

Production Example 6

Production of Thermoplastic Polyurethane Resin Particles (A-3)

[0089] Into a reaction vessel were charged and mixed the prepolymer
solution (U-1) obtained in the production example 3 (100 parts) and the
MEK ketimine compound obtained in the production example 1 (0.7 parts),
and thereto was added 300 parts of an aqueous solution in which a
polycarboxylic acid type anionic surfactant (Sansparl PS-8, manufactured
by Sanyo Chemical Ind., Ltd. (30 parts)) was dissolved. An Ultra
Disperser manufactured by YAMATO Scientific Co., Ltd. was then used to
mix these components at a rotation number of 10000 rpm for 1 minute. The
mixture was then transferred to a reaction vessel equipped with a
thermometer, a stirrer and a nitrogen blowing tube. After the inside of
the vessel was purged with nitrogen, the reaction was performed under
stirring at 50° C. for 10 hours. After the reaction was completed,
the resultant was separated by filtration and dried to obtain
thermoplastic polyurethane resin particles (A-3). The (A-3) had an Mn of
20000, a concentration of urea group of 2.6 weight % and a volume average
particle size of 100 μm.

Example 1

[0090] Into a 100L Nauta Mixer were charged 100 parts of the above
described (A-1) and 10 parts of a polyethylene glycol dibenzoate [Sanflex
EB300, manufactured by Sanyo Chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.22 part of fine
particles of methyl methacrylate ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-1).
The extent of surface coverage of the (D-1) was 20% and the ratio of
volume average particle size was 467. In addition, the polyurethane resin
molded article obtained from the (D-1) had a degree of tensile elongation
of 590% and a tensile strength of 9.0 MPa.

Example 2

[0091] Into a 100 L Nauta Mixer were charged 100 parts of the above
described (A-1) and 10 parts of a polyethylene glycol dibenzoate [Sanflex
EB300, manufactured by Sanyo Chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.40 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-2).
The extent of surface coverage of the (D-2) was 36% and the ratio of
volume average particle size was 467. In addition, the polyurethane resin
molded article obtained from the (D-2) had a degree of tensile elongation
of 540% and a tensile strength of 8.2 MPa.

Example 3

[0092] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-1) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo Chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.20 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 100 nm; Ganz Pearl PM-010J, manufactured by Ganz Chemical Co., Ltd.]
(C-2), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-3).
The extent of surface coverage of the (D-3) was 55% and the ratio of
volume average particle size was 1400. In addition, the polyurethane
resin molded article obtained from the (D-3) had a degree of tensile
elongation of 500% and a tensile strength of 7.6 MPa.

Example 4

[0093] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-1) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo Chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.29 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 100 nm; Ganz Pearl PM-010J, manufactured by Ganz Chemical Co., Ltd.]
(C-2), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-4).
The extent of surface coverage of the (D-4) was 79% and the ratio of
volume average particle size was 1400. In addition, the polyurethane
resin molded article obtained from the (D-4) had a degree of tensile
elongation of 450% and a tensile strength of 7.1 MPa.

Example 5

[0094] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo Chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.20 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-5).
The extent of surface coverage of the (D-5) was 23% and the ratio of
volume average particle size was 633. In addition, the polyurethane resin
molded article obtained from the (D-5) had a degree of tensile elongation
of 580% and a tensile strength of 8.8 MPa.

Example 6

[0095] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.40 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-6).
The extent of surface coverage of the (D-6) was 46% and the ratio of
volume average particle size was 633. In addition, the polyurethane resin
molded article obtained from the (D-6) had a degree of tensile elongation
of 520% and a tensile strength of 8.0 MPa.

Example 7

[0096] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.20 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 100 nm; Ganz Pearl PM-010J, manufactured by Ganz Chemical Co., Ltd.]
(C-2), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-7).
The extent of surface coverage of the (D-7) was 69% and the ratio of
volume average particle size was 1900. In addition, the polyurethane
resin molded article obtained from the (D-7) had a degree of tensile
elongation of 490% and a tensile strength of 7.6 MPa.

Example 8

[0097] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.20 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 100 nm; Ganz Pearl PM-010J, manufactured by Ganz Chemical Co., Ltd.]
(C-2), and the components were mixed at a peripheral speed of 2.2 m/s to
obtain a polyurethane resin powder composition for slush molding (D-8).
The extent of surface coverage of the (D-8) was 69% and the ratio of
volume average particle size was 1900. In addition, the polyurethane
resin molded article obtained from the (D-8) had a degree of tensile
elongation of 490% and a tensile strength of 7.5 MPa.

Example 9

[0098] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-3) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.40 part of fine
particles of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-9).
The extent of surface coverage of the (D-9) was 24% and the ratio of
volume average particle size was 333. In addition, the polyurethane resin
molded article obtained from the (D-9) had a degree of tensile elongation
of 580% and a tensile strength of 8.9 MPa.

Comparative Example 1

[0099] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-1) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.20 part of a fine
particle of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-1').
The extent of surface coverage of the (D-1') was 18% and the ratio of
volume average particle size was 467. In addition, the polyurethane resin
molded article obtained from the (D-1') had a degree of tensile
elongation of 620% and a tensile strength of 9.2 MPa.

Comparative Example 2

[0100] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 0.75 part of a fine
particle of methyl methacrylate-ethyleneglycol dimethacrylate copolymer
[copolymerization ratio of 95:5 (ratio by weight), primary particle size
of 300 nm; Ganz Pearl PM-030, manufactured by Ganz Chemical Co., Ltd.]
(C-1), and the components were mixed at a peripheral speed of 1.0 m/s to
obtain a polyurethane resin powder composition for slush molding (D-2').
The extent of surface coverage of the (D-2') was 86% and the ratio of
volume average particle size was 633. In addition, the polyurethane resin
molded article obtained from the (D-2') had a degree of tensile
elongation of 350% and a tensile strength of 4.8 MPa.

Comparative Example 3

[0101] Into a 100 L Nauta Mixer were charged 100 parts of above described
(A-2) and 10 parts of a polyethylene glycol dibenzoate [Sanflex EB300,
manufactured by Sanyo chemical Industries, Ltd.], and then these
components were mixed at 70° C. for 3 hours. Then, there was
charged 0.1 part of a modified polydimethylsiloxane [KF96, manufactured
by Shin-Etsu Chemical Co., Ltd.] and after 1 hour of mixing, it was
cooled to room temperature. Then thereto was added 1.00 part of a silica
[primary particle size of 3000 nm; Ciblock S200, manufactured by Grace
Japan Co., Ltd.] (G-1), and the components were mixed at a peripheral
speed of 1.0 m/s to obtain a polyurethane resin powder composition for
slush molding (D-3'). The polyurethane resin molded article obtained from
the (D-3') had a degree of tensile elongation of 240% and a tensile
strength of 3.5 MPa.

[0102] The composition ratio of the polyurethane resin powder composition
of Examples 1 to 9 and Comparative Examples 1 to 3, volume average
particle size, extent of surface coverage and peripheral speed of
impeller at the time of mixing (A) and (C), are shown in Table 1.

[0103] The extent of surface coverage of a surface of (A) with (C) was
measured by the above described method.

[0104] The measurement of the radius of the primary particle of (C) was
performed by using a scanning electron microscope (S-800: manufactured by
HITACHI Ltd.) over 50 particles.

[0105] The surface area of (A) was calculated from the particle size
distribution which is divided into 35 sections. The particle size
distribution was obtained by using Microtrac HRA Particle Size Analyzer
9320-X100 (manufactured by Nikkiso Co., Ltd.) with 0.3 to 0.5 ml of the
sample mixture prepared by charging 20 g of the particle sample into 100
ml of 2% aqueous solution of Sansparl PS-8 (manufactured by Sanyo
Chemical Industries, Ltd.) and mixed for 5 minutes or more.

[0106] The calculated results of the extent of surface coverage are shown
in Table 2.

<The measurement of Degree of Tensile Elongation and Tensile Strength
at 25° C.>

[0107] Three dumb bell test pieces No.1 according to JIS K6301 were
punched out from the molded outer skin, and gauge lines of 40 mm interval
were applied at the center of the each sample. The thickness was measured
at the 5 points between gauge lines and the minimum value was adopted as
the thickness. The sample was placed to an autograph in the atmosphere of
25° C., then the tensile test was performed at the tensile speed
of 200 mm/min and the maximum degree of tensile elongation and the
strength at break were calculated. If the tensile strength is 4.9 MPa or
less, the possibility of rupturing at a position other than rupture
openings increases upon airbag deployment.

<Measurement Method of Number Average Molecular Weight>

[0108] The thermoplastic polyurethane resin particles were added to DMF so
that the concentration of the thermoplastic polyurethane resin particles
became 0.0125 weight %, stirred at 80° C. for 1 hour, filtered
under pressure using a filter of 0.3 μm pore size. The thermoplastic
polyurethane resin particles contained in the obtained filtrate was
measured by a gel permeation chromatography using dimethylformamide as a
solvent and polystyrene as a molecular weight standard.

[0109] The molded article obtained from the polyurethane resin powder
compositions for slush molding (D-1) to (D-9) of the Examples 1 to 9 had
the degree of tensile elongation of 600% or less and had the large
tensile strength as well, revealing the excellence in the property upon
airbag deployment. On the other hand, (D-1') of the Comparative Example 1
had the degree of tensile elongation of 600% or more and (D-2') of the
Comparative Example 2 and (D-3') of the Comparative Example 3 had small
tensile strength.

INDUSTRIAL APPLICABILITY

[0110] The molded article using the polyurethane resin powder composition
for slush molding of the present invention, for example, outer skins can
be suitably used as automotive interior materials, including outer skins
for an instrument panel, a door trim and the like.

Patent applications by Yasuhiro Tsudo, Kyoto-Shi JP

Patent applications by CALSONIC KANSEI CORPORATION

Patent applications by SANYO CHEMICAL INDUSTRIES, LTD.

Patent applications in class Carbonyl of a carboxylic acid or ester group directly attached to an aryl group, e.g., dipropylene glycol dibenzoate, etc.

Patent applications in all subclasses Carbonyl of a carboxylic acid or ester group directly attached to an aryl group, e.g., dipropylene glycol dibenzoate, etc.